Raquel Cobos Campos, Pharm 1 ; Naiara Parraza Diez, Pharm, PhD 1 ; Felipe Aizpuru Barandiaran, MD, PhD 1,2,3

ORIGINAL RESEARCH WOUNDS 2013;25(9):256-262 From the 1 Health Research Unit of Álava, Basque Health Service, Álava, Spain; 2 Network Center for Biomedical Research in Epidemiology and Public Health, Granada, Spain; 3 University of the Basque Country, Álava, Spain Address correspondence to: Felipe Aizpuru Barandiaran, MD, PhD José Achótegui s/n 01009 Vitoria-Gasteiz Álava, Spain Felipeesteban.aizpurubarandiaran@ osakidetza.net Disclosure: The authors disclose no financial or other conflicts of interest. 256 WOUNDS www.woundsresearch.com Platelet-Rich Plasma in Skin Ulcer Treatment Raquel Cobos Campos, Pharm 1 ; Naiara Parraza Diez, Pharm, PhD 1 ; Felipe Aizpuru Barandiaran, MD, PhD 1,2,3 Abstract: Introduction. Chronic vascular are associated with a high use of resources. Conventional consists of wound cleansing, necrotic tissue debridement, prevention, diagnosis, and, if necessary, of infection and dressing application; although conventional has limited effectiveness with wound healing (around 15-30%). 8-11 Platelet-rich plasma, used in various fields of medicine, improves chronic vascular ulcer results, but is more expensive. Methods. A cost-effectiveness analysis was performed using a 48-week period comparing plateletrich plasma with standard care. A meta-analysis of papers identified by a literature search was done. Results. A combined measure of effectiveness at 12 weeks for each option was calculated and served as the basis for estimating the probability of healing at 48 weeks with a Markov model. Conclusions. The probability of healing and associated costs were 56% and 5224 using platelet-rich plasma and 31% and 5133 with usual care. The incremental cost that must be assumed to achieve additional healing with platelet-rich plasma is 364. Key words: varicose, skin, platelet-rich plasma, cost-benefit analysis Chronic vascular require multidisciplinary management that is associated with a high use of resources, especially in primary care. It is estimated that in Western countries 1% of adults will have a chronic vascular ulcer at some stage in their lives, the prevalence being 1.3 to 3 individuals out of 1000. 1 In Spain, according to the first national study on leg carried out between 2002 and 2003, the prevalence of vascular was found to be 1.65 per 1000. 2 Vascular can be arterial, venous, or both, with the most common etiology being venous and representing 80%-90% of all vascular. 3,4 Venous tend to be persistent among patients with venous, 30% have a > 5-year history of this condition and an estimated 72% rate of recurrence. 5,6 The conventional of vascular consists mainly of wound cleansing; debridement of necrotic tissue; prevention; diagnosis; and, if necessary, of infection and application of dressings. 7 The effectiveness of the conventional is still relatively low, around 15%-30%. 8-11,22 Moreover, the mean duration of skin is approximately 1 year, indicating the seriousness of the problem for many patients, given the associated pain and disability. The use of platelet-rich plasma () and plasma rich in growth factors

Table 1. Clinical trials included in the meta-analysis. Authors Groups Focus of the Period of (weeks) Number of patients and treated Driver et Control: Usual Diabetic 12 Control: 19 al, 23 2006 care : 16 (adjusted for the autologous initial size of the ulcer) Friese et al, 8 Control: Usual Diabetic 12 Control: 21 2007 care : 20 autologous >>> Knighton Control: Usual Chronic 8 Control: 11 et al, 9 1990 care patients (13 ) autologous : 13 patients (21 ) Aguirre Control: Usual Chronic 8 Control:11 (personal care PRGF: 12 communication) PRGF *Aguirre Control:11 (personal PRGF: 12 communication) Estimated at 12 weeks Steed DL, 10 Control: Chronic 20 Control: 57 1995 placebo gel diabetic PDGF: 61 rhpdgf **Steed DL Control: 57 Extrapolated PDGF: 61 to 12 weeks (PRGF) is a relatively new approach considered clinically useful in various fields of medicine (ie, dentistry, traumatology, cosmetic surgery, ophthalmology, and dermatology). Platelets contain proteins, known as growth factors, that trigger biological effects including directed cell migration (ie, chemotaxis), angiogenesis, and cell proliferation and differentiation, which are key in the processes of tissue repair and regeneration. Various studies have been published on the role of platelet concentrates in the of skin with positive results in favor of this technology. 8-13 Healed n (%; 95% CI) P value 8 (42.1; 19.9-64.3) 13 (81.3;54.5-96.0) P = 0.036 5 (24;5.7-42.0) 11 (55;33.2-76.8) 2/13 (15.4;1.9-45.5) P < 0.005 17/21 (81;64.2-97.7) P < 0.0001 3 (23; 1.0-53.6) 6 (50; 21.7-78.3) P = 0.4 5 (45.5;16.1-74.9) 9 (75;50.5-99.5) 14 (24.6; 13.4-35.7) 29 (47.6; 35.1-60.1) 6 (10.5; 3.0-18.5) 18 (29.5;18.1-41.0) P = 0.01 P = 0.0198 >>> Study was not included in the final cost-effectiveness analysis; *Estimation of the results at 12 weeks from the data at 8 weeks; **Extrapolation from the graph. However, since this biotechnological approach has higher associated costs than conventional practice, it is necessary to assess whether it is economically justifiable through costeffectiveness analysis comparing it with the usual provided in clinical practice. The current use of health care resources for the of vascular is very high, both because complete closure of the wound is very difficult to achieve and because the tend to recur. 14 In a study carried out by Ragnarson Tennvall et al, 15 it was estimated that the Vol. 25, No. 9 September 2013 257

Keypoints Various studies have been published on the role of platelet concentrates in the of skin with positive results. 8-13 Since this biotechnological approach has higher associated costs than conventional practice, it is necessary to assess whether it is economically justifiable through cost-effectiveness analysis. average cost of standard for venous was 71 per patient per week, excluding inpatient care, and 103 in total. In the United Kingdom, the direct cost of vascular leg to the National Health Service has been estimated to be 400 million sterling. 16 Given all this, it necessary to analyze different options, in terms of their associated costs and effectiveness. 258 WOUNDS www.woundsresearch.com Methods A cost-effectiveness analysis comparing 2 options usual clinical practice and for the of skin after 48 weeks was done. Markov-based modeling that allows simulations of complex systems, 17 such as health care processes, was used. The model was constructed following a previously established protocol, using estimations obtained from published or other available data on efficacy, toxicity, and costs of the various options being compared. 17 The clinical course of the was modeled using a hypothetical cohort of 200 patients with characteristics similar to those included in the clinical trials comparing the 2 options reviewed in this study (conventional and ): patients with diabetes between the ages of 55 and 75 years, who have at least 1 ulcer on the lower extremities that had been detected at least 4 weeks earlier, and with a current area of 3 cm 2-10 cm 2. These 200 patients were randomly allocated to receive either 1) usual care: cleansing of the wound; debridement of necrotic tissue; prevention; diagnosis; and, as required, of infection and the application of suitable dressings; or 2) : cleansing of the wound; debridement of necrotic tissue; prevention; diagnosis; and as required, of infection and application of as well as suitable dressings. The applied to these hypothetical cohorts consisted of 12-week cycles with 2 appointments per week. At each appointment, the wound was cleaned appropriately and covered with a suitable dressing. Additionally, the intervention group received on 1 of the 2 days, always on the same day of the week. Once the first 12-week cycle of had been completed, patients in whom complete healing had been achieved were considered to have finished their and were monitored for the remaining 36 weeks to detect potential recurrences. Patients whose wound had not completely healed after 12 weeks, in either of the groups, continued with the conventional until the ulcer was fully healed. Similarly, patients in whom the ulcer recurred after healing received the conventional until the new ulcer was fully healed. Estimation of effectiveness. To obtain data on effectiveness, a literature search was conducted in secondary databases PubMed, EMBASE, and Cochrane, using the following strategy: ( wound healing[mesh] OR leg [mesh] OR skin [mesh] OR venous [mesh] ) AND ( plasma rich in growth factors[mesh] OR platelet rich plasma[mesh] ) AND ( clinical trial[mesh] OR controlled randomized trial [mesh]). Only published original papers and unpublished preliminary results provided by researchers describing studies involving a control group that received conventional (ie, wound cleansing, debridement, infection management, and application of suitable dressings) and lasting for 8 to 12 weeks were selected. No restrictions were applied in terms of language or date. Research that considered a measure of effectiveness other than the number of healed at the end of the study were excluded. A meta-analysis was performed on the data in the selected papers to obtain combined effectiveness results after 12 weeks for each of the options. This was used as a starting point to estimate the probability of healing at 48 weeks. For this estimate, the authors used a Markov model with 4 possible levels of health status: nonhealed ulcer, healed ulcer, recurrence (of the ulcer), and amputation (Tables 1 and 2), and 4 cycles of 12 weeks each. The probability of healing was different in each cycle, while the period for which each patient had a given health status depended on their group allocation and the time elapsed since the start of the. 18 Each patient in each group began the study with the status of nonhealed ulcer. During each cycle in which the patients had this status, their ulcer might heal or not. In the latter case, amputation might then be required. If patients had the status of healed ulcer, they either continued to have no or their ulcer recurred. Table 2 summarizes the probability of changing between health status categories. Estimation of costs. The economic analysis was performed from a health system perspective. The authors only took into account direct costs based on nursing staff wages from Lazaro-Martinez et al 19 for the Spanish publish health

Table 2. Probabilities of changing between health status categories. Treatment At 12 weeks At 24 weeks At 36 weeks At 48 weeks Recurrence* Amputation** Usual 0.222 0.778 0.08 0.92 0.072 0.928 0.064 0.936 0.26 0.16 Usual + 0.468 0.532 0.123 0.877 0.042 0.958 0.038 0.962 0.04 0.16 *Percentage relative to cases in which the ulcer healed. **Percentage relative to cases in which the ulcer did not heal. Table 3. Direct costs included in the cost-effectiveness analysis per ulcer. Usual care Usual care + Number of visits 24 (wound cleansing, debridement, application of dressings) 12 (wound cleansing, debridement, application of dressings) 12 (wound cleansing, debridement, application of dressings + ) Duration of the 15 min 15 min 60 min appointment Cost of the 3.42 * 3.42 * 13.69* appointment Change of 7.20** 7.20** 7.20** Dressing Kit preparation 132.90*** TOTAL 254.88 1972.92 Mean cost of amputations 41163**** *Salary of the nursing staff of the public health system in 2007 after conversion from US dollars to euros. 20 **Average costs of the material necessary for changing dressings based on data from Sweden and United Kingdom. 21 *** Average price of a kit per session. ****Cost of amputations. 22 The conversion was made using the official value of the US dollar and the euro of European Central Bank on October 26, 2012. care system in 2007, and converted into euros; the mean cost of a kit per calculated from the price of 4 different formulations, in some cases from quotes provided by the corresponding supplier, and in others, as advertised on the company website; costs of the materials necessary for changing dressings, taken from Ragnarson and Hjelmgren, 20 using the average between costs in Sweden and the United Kingdom; and costs of amputations 21 due to not healing. Table 3 shows a breakdown of all costs included in study. Statistical analysis. The heterogeneity of the studies selected was examined with the DerSimonian and Laird method, 22 assessing the level of variability in the results across the studies. Given the low power of the test, the authors decided to reduce the level of confidence to 90%. The authors calculated the number needed to treat (NNT) at the 95% level of confidence (the number of to be treated using to achieve a higher rate of healing than that with usual care), and the incremental cost (the increase in costs associated with adding to the usual care to heal 1 more ulcer). The measure of effectiveness used was the number of healed after 48 weeks, expressed in absolute numbers, with the percentage distribution and 95% confidence intervals (CIs), and the costs were calculated in euros. It was not considered necessary to adjust costs or benefits to present values given that the study period was less than 1 year. 20 A sensitivity analysis was performed recalculating the NNT and incremental cost with the CI percentages corre- Vol. 25, No. 9 September 2013 259

Keypoints Using a Markov model, the authors simulated the clinical course of skin with a hypothetical cohort of 200 patients randomly assigned to either receive standard care or to receive platelet-rich plasma () plus standard care. After 48 weeks of, the overall estimates of effectiveness were 56% for the group and 31% for the standard care group, while the estimated costs were 5224 and 5133, respectively. sponding to the measure of effectiveness for each option for which the difference between the outcomes with the 2 s was the smallest. Results Assessment of the effectiveness. In the literature search, the authors identified 5 randomized clinical trials (as communicated by JJ Aguirre, Biotechnology Institute, Vitoria, Spain, in an email dated September 2011) 8-10,23 in which the period was between 8 weeks and 12 weeks. The DerSimonian and Laird method yielded a P value of 0.0963, indicating a lack of statistical homogeneity. After excluding the study by Knighton et al, 9 which contributed the most to the observed heterogeneity, the combined results gave rates of healing of 46.8% (37.4%-56.2%) among those treated with and of 22.2% (14.4%-30.1%) among those receiving standard care. The estimated probabilities of healing after 48 weeks, as assessed using the Markov model, were 56% (46.3%-65.7%) and 31% (21.9%-40.1%) for the and standard care groups, respectively. Assessment of costs. Total ulcer-related costs after 48 weeks of averaged 5224 and 5133 in the and standard care groups, respectively. In the group that received standard care, a high percentage of the figure is due to amputation-related costs, these being higher than in the other group due to the lower rate of healing. The NNT was 4 (95% CI: 3 to 9), which is statistically significant, and the incremental cost to achieve the healing of 1 additional ulcer, when compared with the results of usual care, would be 364. Sensitivity analysis. For the sensitivity analysis, the authors selected the most unfavorable data, that is, the CI percentages corresponding to the measure of effectiveness for each option that minimized the difference in outcomes with the 2 s. Hence, for the standard care group the authors used a probability of healing of 40.1% (40.1 ) and for the group a value of 46.3% (46.3 ). With these new figures, the NNT and 260 WOUNDS www.woundsresearch.com incremental cost was recalculated. In this case, the NNT was 16 (95% CI: -13 to 5), that is, to achieve healing of 1 additional ulcer, compared to the outcome with usual care, 16 more patients should be treated, and taking the worst case scenario, this would increase expenditure by 1456. In this new scenario, the difference between the 2 s is not statistically significant. Further, 1 of the 95% confidence limits is negative, indicating that could have a detrimental effect, ( achieves less benefit than conventional, which is referred to as the number needed to harm). 24 Discussion Using a Markov model, the authors simulated the clinical course of skin with a hypothetical cohort of 200 patients randomly assigned to either receive standard care consisting of cleansing of the wound, debridement of necrotic tissue, prevention, diagnosis, and if required, of infection, and the application of suitable dressings; or to receive in addition to standard care. The effectiveness and costs of the 2 options after 48 weeks was then compared. After 48 weeks of, the overall estimates of effectiveness were 56% for the group and 31% for the standard care group, while the estimated costs were 5224 and 5133, respectively. The NNT was 4 patients. Adding to usual care to achieve healing of 1 additional ulcer required an additional cost of 364, rising to 1546 in the worst case scenario (calculating the incremental cost using data from the literature giving the smallest difference in effectiveness between the s). Furthermore, it should be borne in mind that in the calculations the authors have only considered the direct costs related to the health system. Indirect costs (such as lost productivity due to absenteeism, or sick leave and transport costs) have not been taken into account since they are difficult to quantify, but given the lower rate of healing and higher rate of amputations among those receiving usual care, it can be assumed indirect costs would be higher in this group. Intangible costs (in particular, deterioration in quality of life caused by patient disability and pain due to the wounds) are particularly difficult to quantify in financial terms, and hence, have not been taken into account in this study. It would, however, be important to assess their impact in future studies, since pain is a symptom which is perceived by patients as a constant reminder of their ulceration and is also hard to control. 25 Intangible costs can also be expected to be higher in the group receiving standard care given the

Table 4. Ulcers healed at 12 weeks: results of the studies included in the meta-analysis. Study Intervention group Control group N (%) 95% CI N (%) 95% CI N (%) 95% CI N (%) 95% CI Driver et al, 23 13 (81.3) 54.5-96.0 3 (18.8) 4.1-45.7 8 (42.1) 19.9-64.3 11 (57.9) 35.7-80.1 2006 Friese et al, 8 11 (55.0) 33.2-76.8 9 (45.0) 23.2-66.8 5 (23.8) 5.6-42.0 16 (76.2) 58.0-94.4 2007 Aguirre 9 (75.0) 50.5-99.5 3 (25.0) 0.5-49.5 5 (45.5) 16.0-74.9 6 (54.5) 25.1-84.0 (personal communication)* Steed DL, 10 18 (29.5) 18.1-41.0 43 (70.5) 59.1-81.9 6 (10.5) 3.0-18.5 51 (89.5) 81.5-97.4 1995** Total 51 (46.8) 37.4-56.2 58 (53.2) 43.8-62.6 24 (22.2) 14.4-30.1 84 (77.8) 69.9-85.6 *Estimation of the results at 12 weeks from the data at 8 weeks. **Extrapolation from the graph. lower rate of ulcer healing. In addition, the values of costs and effectiveness have been estimated for a time period of just under 1 year. An ulcer that has not healed after 52 weeks of is considered unlikely to heal; however, the costs continue to increase since the probability of amputation at 5 years is 19%, 18 so the overall costs associated with treating an ulcer after 5 years would be higher, especially in the group receiving the standard care, since there would be a higher rate of amputation. Another important factor to take into account is the limited number of clinical trials identified with the required outcome variable as the main assessment criterion. Further more, of the 4 studies reviewed, only 1 other made reference to vascular, with the other 3 focusing on the use of in diabetic. In theory, this is unlikely to pose a problem given that diabetic have a poorer prognosis than vascular ones in general, and it can be assumed that if is effective in diabetic, it would be at least as effective, or more effective, in vascular. In addition, in 2 of the 4 selected studies, the authors have estimated the number of healed at 12 weeks from the available data for 8 weeks and 20 weeks. This estimate has been performed considering the process of wound healing follows linear kinetics, but in actuality, wound healing depends on several factors such as age, infection presence, degree of nutrition, and length of time since development of the ulcer. Despite the aforementioned limitations, the authors think this study has strengths. In particular, a thorough search of the scientific literature selecting the most homogenous studies was conducted, which allowed the authors to calculate a robust combined estimate of effectiveness, the starting point for the estimate of the probability of healing after 48 weeks of. Further, the authors selected as the measure of the effect an outcome variable, namely the number of healed at the end of the study, that made the criteria for this study s literature search more exacting, as in many studies the variable measured is the percentage reduction in ulcer size. It would be interesting to perform a cost-effectiveness analysis within a clinical trial in order to address the aforementioned limitations. Further, it would be desirable to assess these s from a social perspective, considering factors important for patients such as quality of life, especially pain, and also to carry out a 5-year followup as completed several years ago by Dougherty, 18 who obtained a positive cost-effectiveness ratio using in diabetic. Conclusion The authors conclude that the use of for the of skin is cost effective; the extra cost for achieving the healing of 1 more ulcer than with usual care would be 364, much lower than the overall long-term costs of treating an ulcer with the usual approach of standard care without ( 5133). References 1. Scottish Intercollegiate Guidelines Network (SIGN). SIGN Guideline 120: Management of chronic venous leg. http://www.sign.ac.uk/guidelines/fulltext/120/index.html. Published August 2010. Accessed August 27, 2013. Vol. 25, No. 9 September 2013 261

2. Torra i Bou JE, Soldevilla Agreda JJ, Rueda López J, et al. Primer Estudio Nacional de Prevalencia de Úlceras de Pierna en España. Estudio GNEAUPP-UIFC-Smith & Nephew 2002-2003. Epidemiología de las úlceras venosas, arteriales, mixtas y de pie diabetic. Madrid: Gerokomos; 2004;15(4). 3. Grupo de Trabajo sobre Úlceras Vasculares de la A.E.E.V. Consenso sobre úlceras vasculares y pie diabético de la Asociación Española de Enfermería Vascular (A.E.E.V.)http://www.companiamedica.com/libros_gratis/enfermeria/enfermeria_vascular.pdf. Published May 2004. Accessed August 27, 2013. 4. Lizundia S, Salaberri Y, Balagué L et al. Ulceras cutáneas: empecemos por abordar las causas (parte 1). 2008; 16(8):41-44. http://www.euskadi.net/r33288/es/contenidos/informacion/cevime_infac/es_cevime/adjuntos/infac_v16_n8.pdf. Accessed August 27, 2013. 5. González-Gómez A. Prevención y calidad de vida en pacientes con úlceras vasculares. Angiología.2003;55(3):280-284. 6. Morales-Gordillo V. Úlceras crónicas en los miembros inferiores. Úlceras venosas. Piel. 2008; 23(4);195-197. 7. Agencia de Evaluación de Tecnologías Sanitarias (AETS), Instituto de Salud Carlos III. Effectividad de los Apósitos Especiales en el Tratamiento de las Úlceras por Presión y Vasculare. http://gesdoc.isciii.es/gesdoccontroller?action=download& id=06/11/2012-bd953649d6. Published November 2001. Accessed August 27, 2013. 8. Friese G, Herten M, Scherbaum WA. The use of autologous platelet concentrate activated by autologous thrombin (APC+) is effective and safe in the of chronic diabetic foot a randomized controlled trial. Poster presented at: Fifth International Symposium on the Diabetic Foot; May 9-12, 2007; Noordwijkerhout, The Netherlands. 9. Knighton DR, Ciresi K, Fiegel VD, Schumerth S, Butler E, Cerra F. Stimulation of repair in chronic, nonhealing, cutaneous using platelet derived wound healing formula. Surg Gynecol Obstet. 1990;170(1):56-60. 10. Steed DL. Clinical evaluation of recombinant human plateletderived growth factor for the of lower extremity diabetic. Diabetic Ulcer Study Group. J Vasc Surg. 1995;21(1):71-81. 11. Aminian B, Shams M, Karim-Aghaee B, Soveyd M, Omrani GR. The role of the autologous platelet-derived growth factor in the management of decubitus ulcer. Arch Iranian Med. 1999;2; 98-101. 12. Aminian B, Shams M, Soveyd M, Omrani GR. Topical autologous platelet-derived growth factors in the of chronic diabetic. Arch Iranian Med. 2000;3;55-9. 13. Anitua E, Aguirre JJ, Algorta J, et al. Effectiveness of autologous preparation rich in growth factors for the of chronic cutaneous. Journal Biomed Mater Res Appl Bioma- 262 WOUNDS www.woundsresearch.com ter. 2008;84(2):415-421. 14. Hospedales J, Ferré J, Mestres JM. Úlceras de las EEII: diagnóstico diferencial y guía de tratamiento. Anales de Cirugía Cardíaca y Vascular. 2001;7(4);253-270. 15. Ragnarson Tennvall G, Hjelmgren J, őlien R. The cost of treating hard-to-heal venous leg : results from a Swedish survey. World Wide Wounds. 2006. http://www.worldwidewounds. com/2006/november/tennvall/cost-of-treating-hard-to-healvenous-leg-.html.published November 2006. Accessed September 2011. 16. London NJ, Donnelly R. ABC of arterial and venous disease. Ulcerated lower limb. BMJ. 2000;320(7249):1589-1591. 17. Rubio-Terrés C, Domínguez-Gil Hurlé A. Análisis coste-efectividad del tratamiento de pacientes con úlceras venosas debidas a la insuficiencia venosa crónica con fracción flavonoica purificada y micronizada y terapia compresiva o con terapia compresiva solamente. Rev Esp Econ Salud. 2005;4(2); 87-94. 18. Dougherty EJ. An evidence-based model comparing the costeffectiveness of platelet rich plasma gel to alternative therapies for patients with nonhealing diabetic. Adv Skin Wound Care. 2008;21(12):568-575. 19. Lázaro-Martínez JL, Aragón-Sánchez FJ, García-Morales E, Beneit-Montesinos JV, Gonzalez-Jurado M. A retrospective analysis of the cost-effectiveness of a collagen/oxidized regenerated cellulose dressing in the of neuropathic diabetic foot. Ostomy Wound Manage. 2010;56(11A):4-8. 20. Ragnarson Tennvall G, Hjelmgren J. Annual costs of for venous leg in Sweden and the United Kingdom. Wound Repair Regen. 2005;13(1):13-18. 21. Apelqvist J, Ragnarson Tennvall G, Larsson J, Persson U. Longterm costs for foot in diabetic patients in a multidisciplinary setting. Foot Ankle Int. 1995;16(7):388-394. 22. DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials. 1986;7:177-188. 23. Driver VR, Hanft J, Fylling CP, Beriou JM. Autologel Diabetic Foot Ulcer Study Group. A prospective, randomized, controlled trial of autologous platelet-rich plasma gel for the of diabetic foot. Ostomy Wound Manage. 2006;52(6):68-74. 24. Primo J. Índices de eficacia de un tratamiento. NNT (II/II). Enfermedad inflamatoria intestinal al día. 2003;2(3):62-66. 25. Green J, Jester R. Health-related quality of life and chronic venous leg ulceration: Part 1. Br J Community Nurs. 2009;14(12):S12-S17.